This invention relates to a material handling machine having a vertically swingable boom, such as a loader, and more particularly to an improved means for connecting the boom lift cylinders to the boom on such a machine.
Industrial loaders used in the construction and mining industries and the like vary in size from relatively small, light duty machines to huge, heavy duty machines having buckets capable of handling in excess of ten cubic meters of material. The larger machines conventionally have articulated main frames having pivotally connected front and rear frame sections respectively supported on front and rear drive wheels, the loader engine and cab normally being disposed on the rear frame section, while the front frame section carries the loader boom. The loader boom is conventionally raised and lowered by means of a pair of hydraulic cylinders having one end connected to the front loader frame section and their piston rod ends connected to transversely spaced boom arms. The boom arms are normally rigidly interconnected by one or more transverse members. Obviously, the boom lift cylinders on the larger machines are relatively large and very large forces are transmitted from the cylinders to the boom arms when the loader is driven into a pile of material that is to be loaded or in breaking out and raising the material after the bucket is loaded.
One way of attaching the cylinder rods to the loader arms has been to provide a yoke on the end of the cylinder rod with a transverse pin extending through the yoke and a portion of the boom arm. In such a case, the cylinder is disposed in the same vertical plane as the loader arm, and a relatively large yoke is required to transmit the forces involved. Also, the single thickness of the boom arm absorbs the entire load.
Another structure for connecting the cylinders to the boom arms has included an eye member with a transverse bore on the end of the cylinder rod and a pair of vertical plates welded to opposite sides of the boom arm, with a transverse pin extending through aligned bores in the two plates and the eye member. Again, in such an arrangement, the cylinders are in the same vertical plane as the boom arms. Obviously, the two mounting plates have to be relatively large and the welds extensive to accommodate the forces involved.